The invention relates to molding apparatus, and more particularly to such apparatus including means for forming a hole or opening in the object being molded.
It is known to use a core to form a hole or opening in an object being molded. The core usually has one or two degrees of draft to allow removal of the core without damaging the molded object. It is also known to use an expandable and contractible core in some molding applications to produce a zero-draft opening.
Attention is directed to the following U.S. Pat. Nos.:
839,818 PA0 1,047,102 PA0 859,681 PA0 1,246,532 PA0 948,540 PA0 1,586,603 PA0 1,023,429 PA0 1,624,712